There is conventionally known a technique of extracting a character by removing an outline portion thereof when an outlined character is included in image data. As a specific method, there is a technique of acquiring a character by first converting image data to a binary image, followed by cutting out a character for each gradation, determining whether the cut-out character is a normal character or an outline character, and performing an image correction of converting the character to the normal character when the character is the outline character. There also exists a technique of performing character recognition on the image data by referring to a plurality of character recognition dictionaries, calculating reliability of the result of the character recognition as a character, and selecting the recognition result with high reliability.
However, it has been difficult in some cases to cut out a character by the conventional method of extracting a character by image processing when the character has a thick outline or is in contact with another character. Moreover, when using the character recognition dictionary, the amount of calculation tends to increase since the calculation is performed by combining the plurality of character recognition dictionaries.